PRODUCTION OF LOW ALPHA RAY LEAD

摘要

PROBLEM TO BE SOLVED: To provide a process for producing a lowαray dose lead having theαray dose extremely lower than theαray dose of the conventional products. SOLUTION: The lead for semiconductor materials having a grade of >=4 nines and a count number of radioactiveαparticles of <=0.05CHP/cm<2> is produced by executing electrolyte refining using the crude lead obtd. by heating and melting lead sulfide together with aluminum having theΑray dose of <=1CHP/cm<2> and a flux in a nonoxidizing atmosphere, thereby subjecting the lead sulfide to desulfurization reduction as anode and sulfamic acid contg. substantially no radioactive isotope as an electrolyte.